Variability and controls of otolith growth in the anchovy of the Bay of Biscay

Type Proceedings paper
Date 2012
Language English
Author(s) Petitgas Pierre1, Grellier Patrick1, Duhamel Erwan1, Masse Jacques1, Doray MathieuORCID1
Affiliation(s) 1 : Ifremer, France
Meeting ICES Annual science conference
Source ICES CM 2012/J:18
Keyword(s) Anchovy, Biscay, Otoliths, Growth, Metapopulation
Abstract Individual fish growth depends on internal population factors such as phenotypic variability as well as external factors such as past environmental conditions (temperature, food) and selective mortality (predation or fishing). In the anchovy, growth in the first year is key to population dynamics as it determines the potential energy allocated to reproduction as well as the capacity to occupy off-shore habitats. Further, in the recent past, the anchovy in the bay of Biscay has experienced collapse and recovery and the role played by growth in this history is unknown. Since 2001 with the spring acoustic survey series PelGas, we have monitored individual fish growth by measuring in the otolith the increments between annual rings, in addition to age determination. These data now allow to analyse the growth patterns in the population as well as the effects of environmental parameters and fishing on the apparent growth of individuals. We show that growth is related to a spatial pattern where smaller and lower growing individuals are more coastal than off-shore larger and faster growers. We evidence a temperature effect on the growth pattern where warm years are also those of faster growth. In contrast, fishing does not seem to affect the apparent growth. We also account for the variability of growth between individuals, which has stayed high throughout the series. The study implies a spatial substructure and segregation in this population where particular habitats could have played a fundamental role for the recovery of the population after its
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Petitgas Pierre, Grellier Patrick, Duhamel Erwan, Masse Jacques, Doray Mathieu (2012). Variability and controls of otolith growth in the anchovy of the Bay of Biscay. ICES CM 2012/J:18.